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Over-scanning in pediatric head CT: prevalence, dosimetric impact, and associated cancer risks
Parvane Tayeb Zadeh1, Farshid Mahmoudi2, Abbas Rezaeian2
1Department of Medical Physics, School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran.
Background:
Pediatric head CT is a common diagnostic tool that exposes radiosensitive organs to ionizing radiation. Children's developing tissues are more vulnerable to radiation-induced harm, making accurate dose and cancer risk estimation essential.
Objective:
To quantify organ-specific radiation doses and lifetime attributable cancer risk (LAR) in pediatric head CT, with a focus on the impact of over-scanning.
Methods:
This retrospective study analyzed 102 pediatric head CT scans performed at three hospitals. Organ doses were estimated using size-specific dose estimates and Monte Carlo simulations. LARs were calculated based on age- and sex-specific risk models. The prevalence and extent of over-scanning were assessed, and their effects on organ doses and cancer risk were analyzed.
Results:
The highest doses were delivered to the brain, eye lenses, oral mucosa, salivary glands, red bone marrow, and thyroid. LARs were highest for thyroid cancer, leukemia, lung, and breast cancer. Risk estimates were inversely associated with age and consistently higher in females. Over-scanning was observed in 77.5 % of cases. Importantly, it occurred exclusively in the caudal direction and significantly increased radiation to non-target organs, especially the lungs, thyroid, salivary glands, and oral mucosa. This led to substantial rises in cancer risk, particularly for thyroid cancer in females (254 %) and in children aged 5-10 years (824 %).
Conclusion:
Over-scanning is a prevalent and preventable source of excess radiation in pediatric head CT. It significantly elevates organ doses and cancer risks, especially in young children, underscoring the need for optimized scan protocols and technologist training.
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